According to Microsoft's Value Indicator chart, this update improves security, and has no effect on reliability, connectivity, compatibility, performance, or battery life.

It's worth noting that there are various aspects to mitigations for Meltdown and Spectre, and this update doesn't fix it alone. Along with firmware, a software fix is necessary. In other words, you'll want to also make sure that you're running the latest version of Windows 10.

There might be a performance impact from this update, as we do know that these firmware fixes will affect devices with Intel's fourth-gen 'Haswell' chips and earlier the most. The Surface Pro 3 uses Haswell, as does the Pro 2, which is not receiving a fix.